As part of an experimental validation of a nuclear forensics methodology for Pu source reactor-type discrimination, destructive analysis has been performed on two irradiated UO2 pellets with different irradiation histories. Analysis has focused on measuring key Sm fission product isotope ratios used in a previously published maximum likelihood methodology to determine the most likely irradiation history of the pellets. A total of 21 Sm isotope ratios were measured within the irradiated pellets, and generally agreed within 20% of the irradiations as simulated using the Monte Carlo Radiation Transport and material depletion code, MCNP6. Results indicate the chosen approach can accurately measure the isotope ratios within 5% experimental error.
We use circular sequences to give an improved lower bound on the minimum number of (≤ k)-sets in a set of points in general
position. We then use this to show that if S is a set of n points in general position, then the number □(S) of convex quadrilaterals
determined by the points in S is at least 0.37553(n4) + O(n3). This in turn implies that the rectilinear crossing number cr(Kn) of the complete graph Knis at least 0.37553(n4) + O(n3), and that Sylvester's Four Point Problem Constant is at least 0.37553. These improved bounds refine results recently obtained
by Abrego and Fernandez-Merchant and by Lovasz, Vesztergombi, Wagner, and Welzl. 相似文献
The bonding structure of carbon films prepared by pulsed laser deposition is determined by the plasma properties especially the change of the kinetic energy. Using double laser pulses the ablation process and the characteristics of the generated plasma can be controlled by the setting of the delay between the pulses. In our experiments, amorphous carbon films have been deposited in vacuum onto Si substrates by double pulses from a Ti:sapphire laser (180 fs, λ = 800 nm, at 1 kHz) and a KrF laser system (500 fs, λ = 248 nm, at 5 Hz). The intensities have been varied in the range of 3.4 × 1012 to 2 × 1013 W/cm2. The morphology and the main properties of the thin layers were investigated as a function of the time delay between the two ablating pulses (0-116.8 ps) and as a function of the irradiated area on the target surface. Atomic force microscopy, spectroscopic ellipsometry and Raman-spectroscopy were used to characterize the films. It was demonstrated that the change of the delay and the spot size results in the modification of the thickness distribution of the layers, and the carbon sp2/sp3 bonding ratio. 相似文献
The transient receptor potential vanilloid subtype 1 (TRPV1) is a non-selective cation channel composed of four monomers with
six transmembrane helices (TM1–TM6). TRPV1 is found in the central and peripheral nervous system, and it is an important therapeutic
target for pain relief. We describe here the construction of a tetrameric homology model of rat TRPV1 (rTRPV1). We experimentally
evaluated by mutational analysis the contribution of residues of rTRPV1 contributing to ligand binding by the prototypical
TRPV1 agonists, capsaicin and resiniferatoxin (RTX). We then performed docking analysis using our homology model. The docking
results with capsaicin and RTX showed that our homology model was reliable, affording good agreement with our mutation data.
Additionally, the binding mode of a simplified RTX (sRTX) ligand as predicted by the modeling agreed well with those of capsaicin
and RTX, accounting for the high binding affinity of the sRTX ligand for TRPV1. Through the homology modeling, docking and
mutational studies, we obtained important insights into the ligand-receptor interactions at the molecular level which should
prove of value in the design of novel TRPV1 ligands. 相似文献
Abstract The effect of fertilization and irrigation on phosphate and metal content in maize was studied in an arable land plot experiment on fertilization effects. A field plot experiment was carried out at the Látókép Farm 15 km from Debrecen. Each treatment consisted of 46 m2 plots, arranged in a randomized block design with four replication, where the basic treatment was fertilization; the additional treatments were crop rotation, irrigation and cultivation. The soil is Calcareous Chernozem with 2.8–3.0% humus content. The depth of the humus layer is 70–90 cm. The N-content and original P-content of the soil is average, but it is rich in K. Besides macroelements, there is no shortage of trace elements. The element content of maize was determined with a Labtam 8440M inductively coupled plasma atomic emission spectrometer after digestion. A relationship between phosphate and microelement contents in plant was studied. A linear relationship between phosphate and magnesium, and some microelement contents can be found. Linear correlation in P and Mg content of maize was found strongest (Fig 1.). 相似文献
Nanocomposite biocompatible hydrogels (NCHG) were synthesised as model systems for in situ cured potentially local drug delivery
devices for curing periodontal infections. The composite consists of the following components: nanoparticles (NPs), matrix
gel, and chlorhexidine (CHX) as antibacterial drug. The NPs were obtained by free radical initiated copolymerization of the
monomers, 2-hydroxyethyl methacrylate (HEMA) and polyethyleneglycol dimethacrylate (PEGDMA), in aqueous solution. The same
monomers were used to prepare crosslinked matrices by photopolymerization. NCHGs were obtained by mixing NPs, monomers, and
drug in an aqueous solution then crosslinked by photopolymerization. Mechanical properties, swelling behavior, and the kinetics
of drug release have been investigated. It was found that compression strength values increased with increasing ratio of the
crosslinker PEGDMA. Incorporation of NPs into the matrix resulted similar compression strength as the matrix hydrogel. The
hydrated NCHGs swelled more slowly but admitted more water. The drug was incorporated in NPs by swelling in CHX aqueous solution
or added to the solution of monomer mixture followed by photopolymerization. Studies of release kinetics revealed that on
average 60% of the loaded drug was released. The most rapid release was observed over a 24 h period for matrix gels with low
crosslinking density. For NCHGs, the release period exceeded 48 h. An unexpected result was observed for NCHGs without drug
in the NPs. In this case, increasing release was observed for the first 24 h. Thereafter, however, the apparent quantity of
detectable drug decreased dramatically. 相似文献